1. Field of the Invention
The present invention relates to a method of splicing metal webs and, in particular, to a method of splicing together the ends of flexible, thin, metal webs.
2. Description of the Related Art
A method of splicing metal webs includes a lap splicing method in which the ends of metal webs are lapped on each other and are spliced together, and a butt splicing method in which the ends of metal webs are butted against each other and are spliced together.
As shown in FIG. 8(a), in a conventional lap splicing method, the end of a metal web 70 is lapped on the end of a metal web 72 and a splice surface 73 thereof is spliced by a two-side adhesive tape or by supersonic waves (FIGS. 4 and 6 of Japanese Patent Publication (Kokai) No. 59-24526).
Also, in FIG. 8(b), there is shown a perspective view of a conventional butt splicing method of splicing metal webs. As shown in FIG. 8(b), the ends of the metal webs 70, 72 are butted against each other and the upper and lower surfaces of the butted splice portion 75 are then spliced by one-side adhesive tapes 76, 76, respectively. (FIG. 2 of Japanese Patent Publication (Kokai) No. 59-24526).
However, in the conventional metal webs splicing method as shown in FIG. 8(a), there is left a difference in level in the splice portion of the webs, which makes it impossible for the spliced metal webs to be brought into smooth contact with a pass roller and the like when they are moved. Also, the thickness of the splice portion is greater than those of the metal webs and, if in the lapped splice surface 73 there is left any unspliced portion, then the lapped splice surface 73 may come off while the metal webs are moved. Further, there is a problem that the lapped splice surface 73 may be in contact with other materials during the movement of the metal webs in a step of treating the metal webs. Moreover, when the treatment step includes a process for treating the surface of the metal webs using a treatment solution, then the treatment solution may come into the clearances in the lapped splice portion 73, which may in turn result in generation of inferior quality in the following steps. In addition, there are produced various disadvantages in the surface treatment step of the metal webs. For example, in a step of coating a light-sensitive layer in manufacturing a plate for use in planography when the metal webs splice portion with a level difference passes, the coating device must be retreated to prevent damage due to its contact with the splice portion, and in case of not retreating due to the level difference, the lapped splice surface 73 has an ill effect on the coated surface thereby causing inferior quality.
Also, as shown in FIG. 8(b), in the conventional butt splicing method, the metal webs are spliced by means of the one-side adhesive tapes 76, 76 and, therefore, in the splice portion 75 thereof there is inevitably produced a level difference corresponding to the thickness of the adhesive tapes 76, 76. This level difference also causes disadvantages similar those in the above-mentioned lap splicing method. Especially, in the butt splicing method, while the spliced metal webs are being moved by the pass rollers or the like during its treating or coating step, the adhesive tapes 76, 76 in the butted portion thereof are shaved by the edges of the butted portions of the metal webs, with the result that the butted splice portion becomes weaker in strength and is easy to be cut off. Further, the metal webs 70, 72 are given bending stresses when they pass over the pass rollers, the bending stresses make it easier for the splice portion 75 to be broken. Such breakage occurs very often especially when a thin metal web having a thickness of 0.1 mm to 0.2 mm is used, or when there is a great difference between the thicknesses of the two metal webs to be spliced together.